Means for calcining hydromagnesite



C. E. OLIVER.

MEANS FOR CALCINING HYDROMAGNESITE.

APPLICATION FILED NOVl I4I i921.

IASQO. Patented Nov. 21, 1922.

2 SHEETS-SHEET l.

Ilia-L- C. E. OLIVER.

MEANS FOR CALCINING HYDROMAGNESITE.

APPLICATION FILED Nov. x4. 1921.

1,436,520. Patented N0v.21,1922.

2 SHEETS-SHEET 2.

. Eig-21.

. of the scrabbling tines Patente Nov.. 2l, 1922.

E CHARLES E. OLIVER, 0F VANCOUVER, BRITISH COLUMBIA, CANADA.

MEANS FOR CALCIN IN G HYDROMAGNESITE.

Application filed November 14, 1921.

To all whom t may concern:

Beit known that I, CHARLES E. OLIVER, citizen of the Dominion of Canada, residing at Vancouver,y in the Province of British Columbia, Canada, have linvented certain new and useful Improvements in Means for Calcining Hydromagnesite, of which the following is a specification. y

This invention relates to a furnace which has been particularly designed for calcining hydromagnesite.. Ordinary methods of calcination are not available with this material owing to its extreme lightness and the microscopic iineness of its particles, and further to the fact that the carbon dioxide is driven off with considerabley yenergy during the earlier stages of calcination, and carries with it the finely divided particles of calcined magnesite.

As the carbon' dioxide gas will readily recombine with the magnesite while it is coolingit is also necessary torprevent the carbon dioxide as driven o, coming in contact with the calcined material.

These several diliculties are overcome in the device, which is the subject of this application, by slowly passing thehydromagnesite continuously in a thinly distributed layer, along a relatively elongated flue, through which gases from a furnace are passed which will heat the walls and roof of the flue to a suiiiciently high temperature, to effect calcination of the material, the hot gases moving in a direction opposite to that of the material, bein calcined, that they may carry the evolvedg carbon dioxide away from the material from which it has been discharged. A

The invention also includes several features advantageous to effective and economic calcinin of this material to which attention will be rawn in the following specification, reference being madeto the drawings by which it is accompanied, in which:

Fig. 1 is a sectional plan of the calcining furnace on the line 1-1 in Fig. 2 with portions removed showing the construction of the platform and the supports beneath.

Fig. 2 is a cross Section on the line 2 2 in Fig. 1.

Fig. 3 is an enlarged detail ofthe hopper feed of the hydromagnesite to the kiln, and Fig. 4 is a detail to an enlarged scale by which the matev are circular curtain .or in from or to the flue in Serial No. 515,119.

rial on revolving platforms of the flue is turned over after initial calcination has been effected.

Fig. 5 is a detail view of a portion of my apparatus hereinafter described.

In these drawings 2 represents the furnace from which the heat for calcination is derived. This furnace delivers its gases into an annular iue 3, the walls and roof of which are lined with refractory material that will stand the dull red heat of calcination and are supported on piers 14. The bottom of this flue 3 is formed by a fiat annular conveyor platform 4 of sheet metal havlng a circular supporting rail 5 secured to its underside about its mid area, which rail rests on roller wheels 6 rotatably mounted in bearings at intervals apart around the circle of the Hue.

Secured 'to the platform 4 to project'downward from it, plates 12, the lower edges of which run in circular troughs 13 yaround the outer and inner side walls of the fiue 3, whichtroughs are filled with a loose material such as sand or calcined magnesite, which ei'ectually prevents any draught' out which the calcination is going on.

On the upper surface of the plate conveyor 4 a layer of bricks or tiles of refractory materal is laid on a layer of magnesite to prevent transmission of the heat of the bricks to the metal platform and to the space beneath it.

This conveyor platform t is rotated from a horizontal shaft 11 which extends diametrically across beneath t-he platform and drives by means of worm gear 10 a vertical shaft 9 on each opposite side. 0n the upper end of each vertical shaft is a pinion 8, the teeth of which mesh with those of a c1rcular rack 7 secured to the supporting rail 5 of the platform.

The furnace gasesas delivered from the furnace 2 into the flue 3, travel around it in the direction of the arrows G to the curtain wall 16, which is carried across the flue clear of the upper surface of the conveyor platform 4 and diverts the` gases into an uptake 15 which delivers them either to the atmosphere or to a chamber for such treatment as may be necessary for the recovery of the carbon dioxide as a by-product.

the outer and inner edges of vso Between the furnace connection and the curtain wall 16 a feed hopper 17 delivers the hydromagnesite in a uniformly distributed' layer across the width of the revolving plat'- form 4. This uniformdistribution is effected by a mechanically rotated feed roller 18 having Hat vridges extending lengthwise along it, which roller is mounted in the lower part of the hopper to move thatside downward vwhich is toward the back edge of the hopper. It thus withdraws measured quantities of the material from the hopper and deposits such upon a delivery plate 19 angularly sloping downward to the platform 4 toward'the direction of its rotation.I The material is thus continuously fed in uniformly measured quantities from the hopkper and is quietly and without disturbance delivered onthe moving platform 4.

Immediately beyond the connection of the furnace 2 to the Hue 3 in the direction of rotation, that is, between that connection and the delivery plate 19 of the feed, is located a provision for continually removing the calcined material from the platform 4. This lremoving means comprises a curtain-wall 20 sloping angularly forward across the upper side of the platform 4, from the inner f to the-outer circle thereof, from which wall the Hue is suspended to rest with their weight on the platform, scraper plates 21, the free ends of which plates rest on a horizontally disposed thin edged plate 22 .secured to the underside of an aperture 26 in a tube 23, in

which tube is rotatably mounted aspiral' conveyor 24. The outer end of the tube 23.

and its conveyor'project outside the wallv of the Hue and deliver into a down-take pipe 25, from the lower end of which the light calcined material is withdrawn and delivered by a draught of injected air into asterage chamber.

The scraper plates 21 sweepJ the .table clear of the calcined materialand by the angle at which they are set deliver it ,to the spiral conveyor 24' for removal from the Hue.

In operation the heat from the furnace 2 is delivered into the Hue 3v at 'a temperature sufficient Vto eH'ect the calcining of the material, and .passes around it in the direction of the arrows G until it encounters the curtain wall 16 and passes to the uptake 15. The platform conveyor 4 on which the hydromagnesite to be calcined is spread in an evenly distributed layer, is rotated in a direction opposite to that of the heated Hue gases. as indicated by the arrows T.

The length of the Hue and 'the rate of movement of the conveyor platform 4 are carefull designed to expose the deposited layer o the plete calcination'.

hydromagnesite to the heat of for a sufficient time to eH'ectcomthe/manner vof delivery of the material` lM5 `on to tha platform it is in a loose condition that willbe readily acted on bythe heat to which it isgradually subjected, for `it will be noted that the platform revolves from the feed 17 in the direction of the arrow T, and passing under the curtain wall 16 is first exposed to the moderate heat adjacent the uptake 15 and therefrom passes slowly to the hotter part where the gases are delivered into the Hue from the furnace 2.

After the greater part of the moisture and carbon dioxide has been delivered from the magnesite and the violent evolution of the gas has ceased, the material may be scrabbled or turned over on the platform without risk of the fine material being carried away with the evolved gases, and such scrabblng will enable the heat to more effectively penetrate the material and effect its complete calcination. v

This scrabbling is effected by a bar 27 extending across the table 4 from which bar tines project downward and backward opposite to the direction of movement to penetrate and loosen the material as it passes under it.

Attention may the calcination of the material is not effected by direct application of the hot Hue gases to it, but by the' radiant heat from the roof and walls of the Hue heated by the furnace ases. v g Attention is also drawn to the fact that the weight of the evolved carbon dioxide being in excess of the Hue gases, the gases as evolved will lie in a more or less clearly deined stratum over the material, so that the material is not directly exposed to the Hue gases until it comes close to the furnace de-V livery where the evolved gases are materially less in quantity. The greater lspecific weight of the `carbon dioxide proves advantageous in the recovery of it as 1t will naturally fall to the lower part-ofy the fluev chamber and may be separately withdrawn -in a comparatively pure state for further treatment.

The advantages of this methodoi calcining this material are that the operationisa continuous one: l'that the hydromagnesite is gradually ex osed to the heat action by which the evolution of the gases is conducted under conditions that effectively pevent the exceptionally light and finely divided micros'co ic particles being carried away with the to be scrabbled to enable the calcining heat complete to reach the underlying parts and be drawn tothe fact'that4 iio iis

the operation of calcination after violent evolution of the ygas has ceased.

Itis also worthy of note that the' operative mechanism b'y which the platform 4 is revolved is heat insulated from the 'Hue` and owing to the Hue being .sup orted-on piers atmospheric air is freely itted to where the operative mechanism fis located,

which prevents warping of the metal parts and tends to greater longevity of the mechamsm.

Having now particularly described my invention, I hereby declare that what I claim as new and desire to be protected in by Letters Patent, is:

l. A calcining means comprising an elongated Hue from a furnace to an uptake, a platform movable along the bottom of the Hue in a direction opposite to that of the furnace gases, means adjacent the uptake for feeding anl evenly distributed layer of the material to be calcined on the surface of the platform, and means adjacent the furnace n connection for removing the entire layer of the calcined material from the platform and from the Hue. l

2. A calcining means comprising an elongated Hue from a furnace to an` uptake, the side walls and roof of said Hue being supported on piers with the underside open to the atmosphere, an endlessl platform movable along they lower part of the Hue in a direction opposite to that of the furnace gases and forming a bottom for the Hue, means for sea-ling the space above the platform from the space beneath, means adjacent f, the uptake for feeding an evenly distributed layer of the material to be calcined on the surface of the platform, and means adjacent the furnace connection for removing the entire layer from the platform and from the Hue.

3. A calcining means comprising an annular Hue, a partltion wall across the Hue, a furnace delivering into the Hueon one side of the cross partition, an uptake from the Hue on the other side of the cross partition, an annular platform movable along the bottom of the Hue beneath t'he partition wall, means for rotating that platform in a direction opposite t0 that of the furnace gases, means adjacent the uptake for feeding an evenly distributed layer of the material-to be calcined on the surface of the platform, and means adjacent the furnace connection for removing `the entire layer of the calcined material from the platform and from the Hue.

4. A calcinin means comprising an annular Hue the side Walls and roof of which are supported on piers, an annular movable platform forming the bottom of the Hue,

means for sealing the space above the platformfrom the space below, a partition wall across the Hue to adjacent the level ofthe platform, a furnace delivering into the Hue on one side of the cross partition, an uptake delivering from the Hue on the other side of the partition, means for rotating the platform in a direction opposite to that of the furnace gases, means adjacent the uptake for feeding an evenly distributed layer of the material to be calcined on the surface of the platform, and means adjacent the furnace connection to the Hue for removing the entire layer of the calcined material from the platform and from the Hue.

5. A calcining means comprising an anular Hue the side walls and roof of which are supported on piers, an annular movable platform forming the bottom of the Hue the edges of which platform are downwardly turned to project into annular grooves formed in the inner and outer walls ofthe Hue in which grooves is a sealing material, a partition wall across the Hue to adjacent the level of the platform, a furnace delivering into ythe Hue on one side o-f the cross partition, an uptake delivering from the Hue on the other slowly rotating the platform in a direction opposite to that of the furnace gases, means adjacent the uptake for feeding an evenly distributed layer of the material to be calcined on the surface of the platform, means'` adjacent the furnace connection to the Hue for removing the entire layer of the calcined material from the platform, and means for delivering it from the Hue.

6, A calcining means comprising an annular Hue, two cross partition walls across the Hue adjacent one another, a furnace delivering into the Hue on one side of the cross partitions, an uptake from the Hue on the other side of the crossl partitions, an annular platform movable along the bottom of the Hue beneath the partition walls, means for rotating that platform -in a direction opposite to that of the furnace gases, means between the cross partitions for feeding an evenly distributed layer of the material to be calcined on the surface of the platform, means between the cross partitions for collecting the entire layer of the calcined material on the platform, and means for delivering the collected material from the platform and from the'flue.

\ In testimony whereof I affix my signature.

CHARLES` E. OLIVER.

side of the partition, means for 

